TRENTON — Assembly Speaker Sheila Oliver (D-Essex) tonight became the fourth major Democrat to throw herself into the race for U.S. Senate.

Oliver, who has been collecting signatures to run for the seat left vacant by the death of Sen. Frank Lautenberg (D-N.J.), has told Democratic leaders she intends to run in the Aug. 13 special primary race.

"She had made it clear to me right now that she has about 1,500 signatures and right now she plans on running," said Assemblyman Jerry Green (D-Union).

Green said Oliver told him she’s running because he is in the Assembly’s leadership as a Speaker Pro Tempore and is the incoming chairman of the Union County Democratic Committee.

The Star-Ledger first reported Oliver's interest in the U.S. Senate seat in January.

The news comes on the same night that many top Democrats gathered at the East Brunswick Hilton to discuss strategies for the upcoming U.S. Senate race. Two sources with knowledge of the meeting said Oliver announced her intentions there.

Green, who was at the meeting, would not discuss what happened behind closed doors and said Oliver told him separately.

The move puts Oliver in a field with Newark Mayor Cory Booker and Rep. Rush Holt (D-6th Dist.). Rep. Frank Pallone (D-12th Dist.) has not officially declared, but the Star-Ledger has reported he is running and he plans a press conference outside the state Division of Elections in Trenton Monday afternoon.

At the meeting, four sources said Democrats also discussed the possibility of filing a lawsuit in federal court to challenge Gov. Chris Christie’s decision to hold a special general election in October instead of one simultaneous with the November general election.

The sources requested anonymity because they were not authorized to discuss a private meeting.